C0579 code meaning
Brake Booster Temperature Sensor B Circuit Low
Chassis system Generic code C05xx codes Check engine light
What C0579 means
Electromechanical brake boosters watch the heat in their motor and power electronics so they can scale back assist before damage; a Hitachi Astemo patent, for example, describes one sensor on the motor and one in the drive circuit, with assist limited above set temperatures. GM reads two temperature channels from its booster: A under P25C6/P25C7, B under C0579/C057A. C0579 means channel B reads too low, which GM treats as a short to ground: under 0.03 V on five consecutive checks within 0.6 s in the 2023 and 2025 tables, Type B with MIL after two trips. GM's 2019 Cadillac XT4 tables use the same voltage with two detections between about 7 and 124 mph, but as Type C without MIL. The booster then runs a protective strategy.
C0579 at a glance
- Check engine lightYes, usually on
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyHard
- Typical labor0.5 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of C0579
- Check engine light after two trips (GM 2023/2025), brake warning
- Brake assist may be reduced as a precaution
- Booster temperature B shows an implausible value on the scan tool
Common causes of C0579
- Most likelyTemperature signal B shorted to ground inside the booster or its harness
- PossibleThermistor shorted, e.g. after overheating
- Less likelyFault in the booster control electronics reading the channel
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Brake booster temp sensor bElectric brake booster
What each part of C0579 means
| C | Chassis system: brakes, ABS, steering and suspension. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 79 | The exact fault in that area. |
What to do next
- Note C0579 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about C0579
What does C0579 mean?
C0579 means "Brake Booster Temperature Sensor B Circuit Low". Electromechanical brake boosters watch the heat in their motor and power electronics so they can scale back assist before damage; a Hitachi Astemo patent, for example, describes one sensor on the motor and one in the drive circuit, with assist limited above set temperatures. It is a generic code, so it means the same on every make.
Is it safe to drive with C0579?
Drive gently and only to a workshop. With C0579 the car can go into limp mode (reduced power) to protect itself.
Will C0579 fail an emissions test?
C0579 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is C0579 to fix?
Difficulty: hard. A typical repair takes 0.5 to 4 hours of work. This is a job for a workshop.
Will C0579 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.